PEORIA, Ariz. -- After weeks of debate, intrigue and what Dan Wilson called “a very tough decision,” the Mariners manager and Seattle’s front office were finally ready to reveal their Opening Day starter on Saturday morning.

Logan Gilbert will take the mound for the March 27 contest against the Athletics at T-Mobile Park, in what will be his first career Opening Day start.

“He's prepared for it, and the smile really told it all for me,” Wilson said.

Added Gilbert, who’s entering his fifth MLB season: “It's something you always dream of.”

Among an assortment of riches within a rotation that is arguably the sport’s best, Gilbert was the clearest choice by production from one season ago, which is typically the leading criterion for this decision. But there was also consideration for veteran Luis Castillo, who’s earned the honor for the past two years and who has repeatedly said how important it is to him.

“Luis Castillo has carried that torch -- and deservedly so -- over the last few years and [that] makes it a difficult decision,” Wilson said. “But the way Luis has handled it is awesome, and he is a true professional.”

Castillo was in Wilson’s office to show support when Gilbert received the news. A taken aback Gilbert didn’t speak for roughly five seconds after Wilson informed him, at which point Castillo leaned toward him and good-naturedly threw out both hands.

“Say something!” Castillo said.

“It’s great to have [Castillo's] presence,” Gilbert said. “He keeps it loose, [an] awesome teammate, that kind of stuff. But he really has kind of put his arm around me at times and helped me and steered me in the right direction.”

Wilson also elaborated on other decision-making factors.

“Obviously, Logan had a big year last year,” Wilson said. “Over 200 innings, and a guy that has stepped forward. You want to reward that, no doubt. But as we said, ‘The Rock’ has been the rock. He gets the nickname because of that. He's been so steady. He's been so consistent. And as I said, has really poured a lot into the young pitchers that we have. That's been his M.O., and he's the veteran of the staff. So, it's hard to see the changing of that a little bit, but he has been tremendous about it all.”

Both Gilbert and Castillo started in split-squad games on Saturday, their fourth start of Spring Training each.

"After we had that conversation, we went over the training room, and just sat down for about half an hour, and I don't think he said one word," Castillo said while laughing through an interpreter. "I'm super happy for him."

Gilbert is coming off a season in which he finished sixth in American League Cy Young Award voting after logging an MLB-high 208 2/3 innings over 33 starts, over which he carried a 3.23 ERA (113 ERA+; MLB average is 100) with 220 strikeouts and 37 walks. He held hitters to a 0.887 WHIP (best in MLB) and a .589 OPS (fourth best).

For an organization that has drafted and developed its entire rotation -- sans Castillo, who was a Trade Deadline acquisition in 2022 -- Gilbert has been the beacon of embodying their philosophies and practices. He is their first homegrown arm to start on Opening Day since Félix Hernández, who did so in 2007 and from 2009-2018.

Asked if he thought about that when he was drafted in 2018, Gilbert said: “I don't even think that crossed my mind, really. It seems so far down the road, and at the time, it was Félix for probably, what, 10 years or something. That's like the epitome.”

As a student of the game who regularly follows some of the sport’s best pitchers, Gilbert has established himself among them.

“I think back to high school and college, and it felt like a holiday on Opening Day,” Gilbert said. “It's the first game of the year; all the best pitchers are out there. So to me -- and I'm an extreme baseball fan so it's probably different -- but I felt like the world stopped for that day, and everybody just had their TV on and watched the best pitchers in the game go at it.”